SLOS is caused by an inborn error of cholesterol biosynthesis. Affected patients have growth and developmental retardation, congenital anomalies, and a characteristic facial appearance. Prior to discovery of the biochemical defect, diagnosis was based on clinical examination alone. Confirmation of the clinical diagnosis can now be accomplished by demonstration of the characteristic abnormal sterol pattern in plasma or other tissues.

To determine which clinical features were important predictors of the presence of the biochemical abnormality, a data sheet was devised and completed for all patients referred for sterol testing. The data sheet included the following: major organ malformations, “minor” anomalies (polydactyly, cleft palate, cataracts), mental retardation, death, and genital anomalies (Bialer scoring system). In addition, a separate section for facial characteristics (ptosis, anteverted nares, micrognathia, bitemporal narrowing) was included. 114 patients had completed data sheets. 45 of the patients were positive, while 69 were negative on biochemical testing.

The most significant predictor of the presence of biochemical defect was the distinctive facial appearance (p=.00001). The presence of the“minor” anomalies was also significant (p<.0001). The total Bialer score, presence of major organ malformations or mental retardation, and genital anomalies did not significantly correlate with the presence of biochemical defect.

This data can now be used to help determine which patients should be referred for biochemical testing. Patients with either polydactyly, cleft palate, or cataracts, in the presence of the characteristic facial appearance are most likely to have the biochemical defect of SLOS